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Advances in methods and algorithms in a modern quantum chemistry program package

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TLDR
Specific developments discussed include fast methods for density functional theory calculations, linear scaling evaluation of energies, NMR chemical shifts and electric properties, fast auxiliary basis function methods for correlated energies and gradients, equation-of-motion coupled cluster methods for ground and excited states, geminal wavefunctions, embedding methods and techniques for exploring potential energy surfaces.
Abstract
Advances in theory and algorithms for electronic structure calculations must be incorporated into program packages to enable them to become routinely used by the broader chemical community. This work reviews advances made over the past five years or so that constitute the major improvements contained in a new release of the Q-Chem quantum chemistry package, together with illustrative timings and applications. Specific developments discussed include fast methods for density functional theory calculations, linear scaling evaluation of energies, NMR chemical shifts and electric properties, fast auxiliary basis function methods for correlated energies and gradients, equation-of-motion coupled cluster methods for ground and excited states, geminal wavefunctions, embedding methods and techniques for exploring potential energy surfaces.

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Switching radical stability by pH-induced orbital conversion

TL;DR: The SOMO-HOMO energy-level conversion (SOMO-HOOMO conversion) as discussed by the authors is known to occur in any distonic radical anion that contains a sufficiently stabilized radical (aminoxyl, peroxyl and aminyl) non-π-conjugated with a negative charge (carboxylate, phosphate, sulfate).
Journal ArticleDOI

Accelerating Resolution-of-the-Identity Second-Order Moller-Plesset Quantum Chemistry Calculations with Graphical Processing Units

TL;DR: The modification of a general purpose code for quantum mechanical calculations of molecular properties (Q-Chem) to use a graphical processing unit (GPU) is reported and a 4.3x speedup of the resolution-of-the-identity second-order Møller-Plesset perturbation theory (RI-MP2) execution time is observed in single point energy calculations of linear alkanes.
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Acid-base mechanism for ruthenium water oxidation catalysts.

TL;DR: In this article, a detailed theoretical study of the pathway for water oxidation in synthetic ruthenium-based catalysts is presented, where experimental observations suggest a purely single-center mechanism.
Journal ArticleDOI

A System-Dependent Density-Based Dispersion Correction

TL;DR: The proposed density-dependent energy correction, dDXDM, dramatically improves the performance of popular density functionals and largely reduces the errors of the parent functionals for both inter- and intramolecular interactions.
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Electron Donation in the Water–Water Hydrogen Bond

TL;DR: This work rationalizes the success of empirical electrostatic potentials by clarifying intermolecular CT effects in the simplest water cluster, the water dimer, based on absolutely localized molecular orbitals (ALMOs), which are ideal for separating CT from frozen density and polarization interactions.
References
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Journal ArticleDOI

Density‐functional thermochemistry. III. The role of exact exchange

TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
Journal ArticleDOI

Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen

TL;DR: In this paper, a detailed study of correlation effects in the oxygen atom was conducted, and it was shown that primitive basis sets of primitive Gaussian functions effectively and efficiently describe correlation effects.

疟原虫var基因转换速率变化导致抗原变异[英]/Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Journal ArticleDOI

General atomic and molecular electronic structure system

TL;DR: A description of the ab initio quantum chemistry package GAMESS, which can be treated with wave functions ranging from the simplest closed‐shell case up to a general MCSCF case, permitting calculations at the necessary level of sophistication.
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